Strain may be viewed as an amount of deformation of a body due to an applied force. The amount of deformation may be a fractional change in the length of the body. Strain can be positive (tensile) or negative (compressive).
Strain can be measured using various methods. In many applications, strain gauges are used to measure strain. For example, strain gauges are often used to measure torque or other forces in an automobile that may cause strain on components in the automobile.
Strain gauges may come in various forms. One common form of strain gauge is a metallic strain gauge. A typical metallic strain gauge varies its electrical resistance in proportion to an amount of strain in the gauge.
More specifically, a metallic strain gauge typically contains a very fine wire or metallic foil arranged in a grid. The grid may maximize an amount of metallic wire or foil that may be subject to strain. A cross-sectional area of the grid may be minimized to reduce an effect of shear strain and Poisson Strain. As strain is applied to the grid, the resistance of the grid may change. An amount of change in the resistance of the grid may be proportional to an amount of strain applied to the grid.